The present invention relates generally to knives having blades pivotally foldable with respect to a casing. More specifically, the present invention relates to knives having a manually actuated button slidably mounted to the casing which, upon a user exerted force, transmits pivotal motion to the blade, as well as translatory movement of the pivot axis relative to the casing.
Folding knives having user actuated, mechanical drives for opening a knife blade pivotally mounted to a casing are well known in the art. Most common among these folding, or pocket type knives are those having a spring loaded, user-actuated, blade release mechanism. Examples of such knives can be readily seen in U.S. Pat. Nos. 4,893,409 to Poehlmann; 4,897,922 to Brooker; and 4,918,820 to Korb, et al. The springs in these knives tend to lose their resiliency over time, therefore making them less economically attractive and less useful. Furthermore, these knives do not include any means for locking the blade in any one position, thereby permitting the risk of accidental opening or closing of the blade.
Another type of prior art folding knife is having a user-actuated button slidably mounted to the exterior surface of the casing. When the user exerts a force to slide the actuator, the force is transmitted to pivot the blade from its closed to its open position.
This type of knife is exemplified in applicant's issued U.S. Pat. No. 4,719,700. The knife disclosed in this patent uses a non-extensible linkage having one end connected to the actuator and its second end wrapped around a wheel connected to the blade. The user exerted force, in this case, is transmitted by the non-extensible linkage to rotate the wheel, thereby pivoting the blade from its closed to its open position.
An alternate embodiment of the above described patent reveals a similar operation using a plurality of intermeshing gears instead of a non-extensible linkage and wheel. Both embodiments utilize a blade locking mechanism typically found in what is known in the art to be "lock back" knives.
A common feature of all conventional folding knives, regardless of the manner of effecting blade movement, is a blade pivot axis which is stationary relative to the casing.